Low resistance probe for semiconductor

Abstract

A probe (10) that can be used for forming a low resistance electrical connection to a semiconductor die includes a contact (18) that is created on a compliant layer (12) which is supported by a substrate (11). Pressure applied to the contact (18) compresses the compliant layer (11) which causes a distal end of the contact (18) to move in a motion that is substantially equal to an arc. As the contact (18) moves through the arc motion, it scrubs across a bonding pad of a semiconductor die and breaks through oxide that typically forms on the bonding pad thereby forming a low resistance electrical connection to the bonding pad.

We claim: 
     
       1. A probe for providing a low resistance electrical connection to a semiconductor die comprising: a rigid substrate that is a printed circuit board having electrical components interconnected on the substrate;   a compliant material covering a portion of the substrate;   a base plate covering a portion of the compliant material wherein the base plate is a trapezoidal shaped conductor that has a first edge that is a long edge, a second edge that is shorter than the first edge and is positioned opposite from the first edge;   a first step conductor layer that covers a portion of the base plate wherein the first step layer has an edge that is aligned with the second edge of the base plate;   a second step conductor layer that covers a portion of the first step layer and has an edge aligned with the second edge of the base plate;   a third step noble metal layer that covers a portion of the second step layer and has an edge aligned with the second edge of the base plate; and   a signal line on the compliant material wherein the signal line is a conductor that forms an electrical connection to the first edge of the base plate.   
     
     
       2. The probe of claim 1 wherein the base plate, the first step layer and the second step layer are a ductile conductor material. 
     
     
       3. The probed of claim 1 wherein the base plate, the first step layer and the second step layer are copper. 
     
     
       4. The probe of claim 1 wherein the substrate is aluminum nitride. 
     
     
       5. The probe of claim 1 wherein the compliant material is a high temperature polymide. 
     
     
       6. The probe of claim 1 wherein the compliant material is a high temperature polyurethane. 
     
     
       7. The probe of claim 1 wherein the first edge of the base plate is approximately one hundred microns long. 
     
     
       8. A probe that is used to provide a low resistance electrical connection to a semiconductor die comprising: a rigid substrate;   a base plate having a first surface, a second surface, and a first edge wherein the base plate is a ductile conductor material;   a tip projecting perpendicular from the first surface of the base plate and aligned to the first edge of the base plate wherein the tip is a conductor material; and   a compliant material covering a portion of the substrate between the second surface of the base plate and the substrate wherein the compliant material compresses under pressure applied by the base plate to allow the base plate to bend which causes a distal end of the tip to move in a pattern that is substantially an arc in order to scrub the distal end of the tip across a bonding pad that is in contact with the distal end of the tip.   
     
     
       9. The probe of claim 8 wherein the base plate has a square shape. 
     
     
       10. The probe of claim 8 wherein the base plate has a triangular shape. 
     
     
       11. The probe of claim 8 wherein the ductile conductor material is aluminum. 
     
     
       12. The probe of claim 8 wherein the substrate is a printed circuit board. 
     
     
       13. The probe of claim 8 wherein the compliant material is a high temperature polyimide. 
     
     
       14. The probe of claim 8 wherein the compliant material has a thickness between fifty and seventy microns. 
     
     
       15. A probe that is used to provide a low resistance electrical connection to a semiconductor die comprising: a rigid substrate;   a base plate having a first surface, a second surface, and a first edge wherein the base plate is a ductile conductor material;   a tip projecting perpendicular from the first surface of the base plate and aligned to the first edge of the base plate wherein the tip is formed from a plurality of layers of conductor material that are formed in a stair step shape; and   a compliant material covering a portion of the substrate between the second surface of the base plate and the substrate wherein the compliant material compresses under pressure applied by the base plate to allow the base plate to bend which causes a distal end of the tip to move in a pattern that is substantially an arc.   
     
     
       16. A method of forming a low resistance probe comprising: providing a substrate;   covering a portion of the substrate with a compliant layer;   covering a portion of the compliant layer with a base plate; and   forming a tip projecting perpendicularly from the base plate wherein the tip is eccentrically positioned on the base plate for the purpose of causing a portion of the base plate to move into a plane of the compliant material which causes a distal end of the tip to move in a substantially arc-type motion for scrubbing the distal end of the tip across a bonding pad that is in contact with the distal end of the tip.   
     
     
       17. The method of claim 16 wherein covering the portion of the compliant layer with the base plate includes applying a ductile conductor onto the portion of the compliant layer. 
     
     
       18. A method of forming a low resistance probe comprising: providing a substrate;   covering a portion of the substrate with a compliant layer;   covering a portion of the compliant layer with a base plate; and   forming a tip by depositing a plurality of conductor layers on the base plate with each successive layer covering a smaller area thereby forming a tip that is wider at an end proximal to the base plate than at a distal end wherein the tip is eccentrically positioned on the base plate for the purpose of causing a portion of the base plate to move into the plane of the compliant material which causes a distal end of the tip to move in a substantially arc-type motion.